This invention relates to mix-heads for two chemically reactive streams and more particularly to such mix-heads for impingement mixing and stream transfer of two or more chemically reactive plastic compositions and wherein the mix-head includes recirculation passages.
Various high pressure mix-heads have been proposed that provide combined recirculation flow and impingement mixing injection and flow from the mix-head to a mold cavity. U.S. Pat. No. 4,175,874 issued Nov. 27, 1979 and U.S. Pat. No. 4,053,283 issued Oct. 11, 1977 disclose such a mix-head wherein the recirculation passages are formed in the piston. U.S. Pat. No. 3,706,515 issued Dec. 19, 1972 utilizes a constant section plunger. A separate movable slide plunger has recirculation paths that are selectively positioned to define a recirculation path between mix-head inlets and recycle outlets.